Biaxial strain system for cultured cells

Abstract

Biological cells plated on an elastic membrane are placed under biaxial strain for purposes of observation by a device that includes a support with an opening over which the membrane is secured, a movable cylinder coaxial with the opening and fitting closely but movably within the opening, and an actuating member that stabilizes and controls the position of the cylinder relative to the opening. The actuating member is coupled to the support by a threaded connection while engaging the movable cylinder. The degree of membrane stretch is accurately controlled by the rotation of the actuating member.

What is claimed is: 
     
       1. Apparatus for imparting biaxial strain to biological cells adhering to an elastic membrane, said apparatus comprising: a membrane support having a tubular passageway with an opening at one end and means for affixing such a membrane across said opening;   a cylinder, open and hollow, terminating at one end in a planar rim, said cylinder disposed inside said tubular passageway, such that said membrane support and said cylinder are on the same side of any such membrane affixed across said opening; and   actuating means coupled to said membrane support through a threaded connection and engaging said cylinder, whereby rotation of said actuating means along said threaded connection causes said cylinder to move longitudinally within said tubular passageway such that said planar rim protrudes through said opening to a degree corresponding to the degree of rotation and engages any such membrane affixed across said opening, thereby biaxially stretching a central portion of said membrane in a planar configuration across said planar rim.   
     
     
       2. Apparatus in accordance with claim 1 further comprising means for limiting movement of said cylinder to a longitudinal direction relative to said tubular passageway. 
     
     
       3. Apparatus in accordance with claim 1 in which said cylinder is defined as a first cylinder, said membrane support is a second cylinder, and said actuating means is a third cylinder encircling said second cylinder, and said threaded connection comprises threads on an internal surface of said third cylinder mated with threads on an external surface of said second cylinder. 
     
     
       4. Apparatus in accordance with claim 3 in which said third cylinder has a flange extending across said second cylinder to contact said first cylinder. 
     
     
       5. Apparatus in accordance with claim 3 further comprising a transparent protective lid sized and shaped to rest atop said first, second and third cylinders. 
     
     
       6. Apparatus in accordance with claim 1 in which said tubular passageway and said planar rim have circular cross sections, thereby imparting equibiaxial strain to said biological cells. 
     
     
       7. Apparatus in accordance with claim 1 in which said planar rim has an elliptical cross section. 
     
     
       8. Apparatus in accordance with claim 1 further comprising a stand to support said membrane support, cylinder and actuating means such that any such membrane affixed across said opening forms the lowermost plane of said membrane support, cylinder and actuating means, and such that said membrane remains at a fixed position relative to said stand regardless of the degree of stretching of said membrane by said cylinder. 
     
     
       9. Apparatus in accordance with claim 1 in which said means for affixing such a membrane comprises a snap ring defined as a rigid ring with a protruding axial rim and a channel in said membrane support surrounding said opening, said channel sized to receive said protruding axial rim in a friction fit. 
     
     
       10. Apparatus in accordance with claim 1 further comprising a ring bearing indicia that indicate relative angular positions, which together with indicia on said actuating means provides a reproducible indication of the degree of rotation of said actuating means and hence the degree of stretch imparted to said membrane. 
     
     
       11. Apparatus for imparting equibiaxial strain to biological cells adhering to a plurality of elastic membranes, said apparatus comprising: a membrane support having a plurality of tubular passageways each with an opening at one end, and means for affixing such membranes thereto with one such membrane across each of said openings;   a membrane stretching member comprising a plurality of cylinders, open and hollow, equal in number to said tubular passageways and arranged in an array complementary to said tubular passageways, each cylinder terminating at one end in a planar rim; and   actuating means coupled to said membrane support through a threaded connection and engaging said membrane stretching member, whereby rotation of said actuating means along said threaded connection causes said cylinders to move longitudinally within said tubular passageways such that said planar rims protrude through said openings to a degree corresponding to the degree of rotation and engage any such membranes affixed across said openings, thereby equibiaxially stretching a central portion of each of said membranes in a planar configuration across said planar rims.   
     
     
       12. Apparatus in accordance with claim 11 further comprising a stand to support said membrane support, membrane stretching member and actuating means such that any such membranes affixed across said openings form the lowermost plane of said membrane support, cylinder and actuating means, and such that said membranes remain at a fixed position relative to said stand regardless of the degree of stretching of said membranes by said cylinders. 
     
     
       13. Apparatus in accordance with claim 11 in which said membrane support has a cylindrical outer surface and said actuating means is a member having a cylindrical inner surface, and said threaded connection comprises threads on said cylindrical outer surface mated with threads on said cylindrical inner surface. 
     
     
       14. Apparatus in accordance with claim 11 further comprising a transparent protective lid sized and shaped to rest atop said membrane support, membrane stretching member and actuating means.